The R* Webmaster has just sent out the official game description for San Andreas, along with the screenshots they have on the official site...
"Five years ago Carl Johnson escaped from the pressures of life in Los Santos, San Andreas... a city tearing itself apart with gang trouble, drugs and corruption. Where filmstars and millionaires do their best to avoid the dealers and gangbangers.
Now, it's the early 90s. Carl's got to go home. His mother has been murdered, his family has fallen apart and his childhood friends are all heading towards disaster.
On his return to the neighborhood, a couple of corrupt cops frame him for homicide. CJ is forced on a journey that takes him across the entire state of San Andreas, to save his family and to take control of the streets."
The original name of the middle image was "carl johnson.tif" giving a fair idea that the main character is indeed black this time around making a refreshing change to the stalwart bad-boy white-guy.
The last paragraph, "...the entire state of San Andreas...", is very interesting - are we going to see a return of more than one city per game, a la the original GTA? Or are R* just bending the truth and there will be different islands a la GTA3 and Vice? Time will tell!
Further in-depth analysis of the shots can be read this thread on the forums and indeed various other places around the net.